As mentioned, above for street use the 3.73 gears are great for the 5 speed manual and 4.10 are better for an AOD auto .

The auto trans is a slush box and the 4.10s really wake it up.

If your planning on the 1/4 mile speedway and you have some good gripping tires the 4.10s on a manual are ok. Other wise you just spin tires.
Some guys find tire smoking impressive, but I find it gets expensive and Im more impressed with using the power to push you down the strip.

That's a good one and like dawson1112 and Boss are saying going with 4.10's will make your 1st non-existent Ford Racing's 3.73's are more than enough to wake the car up! I'm not sure if you're a T5 or AOD but be sure to check out the Speedo gears as well (<-Just for example) as your speedo will be off (I never swapped mine in the past but it's a good idea to do so)

5spd, 6spd and AOD are all close in final drive ratio. .62 to .82 I belive.
You can pop your numbers into a virtual dyno and see where your at!
Ah its just fun! Watch the heat you can cook your
cool juice( anti freeze) and over heat

I had 4:10s in my 08 GT vert - def woke it up and I loved it.
Gas mileage - not so much, could have used a 6th gear there.

Hey AzDevil1,

Thanks for bringing this up!!!

We price match here at AmericanMuscle- So if you're to ever see something listed elsewhere for less shoot us a call and we'll have a match setup. I'll be sure to have this forwarded over to the appropriate team right now so we can have that sorted.